1. Field of the Invention
The present invention relates to seat adjustment mechanisms that use a rotating handle. Manually adjusting the incline of vehicle seats is their primary use.
2. State of the Art
Several manual systems may adjust vehicle seat backs. A common adjustment mechanism is a releasable lock. With that system, the person in the seat pulls or pushes on a lever, which in turn releases a lock. The person then either leans forward or backward until the seat is at a proper incline. He or she then releases the lever to relock the lock and secure the seat back.
Another common manual seat adjuster is a rotary handle. Instead of releasing the seat and relying on the person to lean to a preferred angle, the rotary handle affects the adjustment directly. The handle has a spur gear that engages a gear on the seat pivot. Handle rotation thuse causes the seat pivot to rotate. The commercial devices may be more complex, but a gear on the handle transmits rotary motion to the seat pivot. Systems like this are more common on European cars than on other vehicles.
Seats can be difficult to adjust using the prior art systems. The handle may be difficult to rotate. Once solution has been to change the gearing, but that often requires too many turns of the handle to effect desired seat recline. As loads increase, the previously mentioned problems becomes more crucial. Force from prior art handles can be applied unevenly on the gear. Also, the force from the rack can act unevenly on one side of the seat. The member that transmits force from the rack to both seat pivots must occupy a specific internal location within the seat, and that location may be inconvenient. The handle also may be located inconveniently for the user to reach.